Messengers from deep Earth: a full-field XRF study of fluid-bearing inclusions in natural micro-diamonds

Recently, a large number of inclusions of hydroxyl members of the humite group were discovered in a unique set of ~100 micronsized diamonds. These hydrated phases might play a crucial role in the distribution of key volatiles in Earth’s mantle. While the hosts for mantle water in the transition zone are relatively well understood, there is a wider variety of potential hydrated phases in the upper mantle. However, until the discovery of the diamonds that are the subject of this proposal, little evidence for the existence of hydrous phases beyond phlogopite and amphibole had been found. Studying hydrous minerals in upper mantle assemblages is thus vital for enhancing our understanding of water transport and storage in the upper mantle. This project will address the complex nature of dense hydrated minerals and their coexisting phases and fluids by determining their major and trace-element composition.